Anti-terror lightweight armor plates and a method of producing same

ABSTRACT

A lightweight armor plate having a contiguous ceramic layer that absorbs and disperses energy from a projectile. Therefore, the ceramic layer is generally considered to be the front of armor plate. The ceramic plate receives the impact of the projectile, such as but not limited to, bullets and shrapnel. In the case of bullets, for example, the tip of the bullet is deformed and the pressure load is reduced by contact with the ceramic plate. Plate further includes a hardened metal layer situated behind, and fixedly attached to, contiguous ceramic layer and designed and constructed to prevent penetration by projectile. The high plastic elasticity of this hardened metal layer completely absorbs the rest of the kinetic energy of the bullet through deformation and heat. Attachment of ceramic layer and hardened metal layer is preferably by use of an adhesive.

This application is a Continuation-In-Part of U.S. patent application Ser. No. 10/861,357 filed 7 Jun. 2004, which is a Continuation-In-Part of U.S. patent application Ser. No. 10/412,312 filed 14 Apr. 2003 and currently pending which claimed priority from U.S. patent application Ser. No. 10/155,670 filed on 28 May 2002 and currently pending which claimed priority from U.S. Patent Application 60/343,213 filed on 31 Dec. 2001 and now abandoned.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to lightweight armor plates and, more particularly, armor plates having only two layers, a contiguous ceramic component and a hardened metal layer, and a method of producing the armor plate.

The recent increase in political unrest, financially motivated crime and/or terrorism in many areas of the world has caused many people to fear that they are potential targets for attack with firearms or explosive devices.

Typically, protection from bullets or shrapnel required use of expensive and heavy armor. True armored vehicles, such as tanks and other vehicles designed to withstand artillery shells and rockets are obviously ill suited to urban travel.

Previously available minor for normal vehicles was typically so heavy that it required use of very large motors and/or all wheel drive transmission systems. This meant that retrofitting a typical passenger vehicle with armor was virtually infeasible.

Further, the cost of typical armoring for a vehicle is prohibitive, owing in part to the types of materials employed and in part to the amount of armor employed.

These considerations also apply to armoring static targets such as buildings, windows and bus stops. Similarly, portable bulletproof protection has typically been limited to “flack jackets” and helmets which offer no protection for the face and often leave arms and legs unprotected.

While use of armor plates which rely upon ceramic components is know (e.g. US. 6,112,635 and U.S. Pat. No. 5,200,256), these references teach use of ceramic beads (i.e. interrupted ceramic layer). Thus, the prior art teaches against use of a contiguous ceramic layer. Use of interrupted ceramic layers has, as an inherent disadvantage, a requirement for orderly assembly, or packing, of the ceramic beads. Assembly, or packing, of the beads introduces an expensive manual labor step into the manufacturing process. Further, these references do not teach the superior qualities of hardened metal layers as detailed hereinbelow.

Further, U.S. Pat. No. 4,760,611 teaches use of a ceramic core entirely covered by a metal envelope. This configuration has, as an inherent disadvantage, a high weight per unit area. Further, initial impact of a projectile according to this reference is against metal, not ceramic material. Such an arrangement fails to take maximum advantage of the force dissipation realized by shattering ceramic material. The envelope is pre-stressed as it cools around the ceramic core so as to inhibit the fragmentation thereof under shock due to the impact of a projectile. This armor element, therefore, includes three protective layers and requires casting as the sole method of production. This requires dedicated molds, costly casting equipment, resulting in a high retail price.

U.S. Pat. No. 4,836,084 discloses an armor plate composite that is composed of four main components, a ceramic impact layer, a sub-layer laminate, a supporting element and a backing layer. It should be noted that each of these main components contain several sub-layers.

There is therefore a widely recognized need for, and it would be highly advantageous to have, lightweight armor plates having only two layers, a contiguous ceramic component and a hardened metal layer, and a method of producing the armor plate devoid of the above limitations.

SUMMARY OF THE INVENTION

The present invention is armor plates having only two layers, a contiguous ceramic component and a hardened metal layer, and a method of producing the armor plate.

According to the teachings of the present invention there is provided, a lightweight armor plate, the plate comprising: (a) a single contiguous ceramic layer; and (b) a single hardened metal layer fixedly attached to the ceramic layer, and the single hardened metal layer is an alloy that contains at least one material selected from the group consisting of aluminum, magnesium, silicon, titanium, copper, manganese and chromium.

According to a further teaching of the present invention, a total thickness of the hardened metal layer and the contiguous ceramic layer is in the range of 12 to 18 mm.

According to a further teaching of the present invention, the alloy is a heat-treated alloy.

According to a further teaching of the present invention, the hardened metal layer includes at least seventy percent aluminum by weight and further includes at least one element selected from the group consisting of magnesium, silicon, titanium, copper, manganese, chromium, zinc, beryllium, tungsten and molybdenum.

According to a further teaching of the present invention, the hardened metal layer is produced by heating the alloy to a temperature in excess of 540 degrees centigrade, followed by cooling the alloy to less than sixty degrees centigrade by immersion in a liquid bath and thereafter precipitation hardening the alloy by heating to a temperature between 100 and 170 degrees centigrade.

According to a further teaching of the present invention, the contiguous ceramic layer includes primarily at least one material selected from the group consisting of Alumina (Al2O3) and Magnesia (MgO).

According to a further teaching of the present invention, the contiguous ceramic layer includes primarily at least one material selected from the group consisting of Alumina (Al₂O₃) and Magnesia (MgO).

There is also provided according to the teachings of the present invention, a method for producing a hardened metal plate for use in an armor plate, the method comprising the steps of: (a) heating an aluminum alloy to a temperature in excess of 540 degrees centigrade; (b) immersing the aluminum alloy in a liquid bath, thereby cooling to less than 60 degrees centigrade; and (c) precipitation hardening by second heating the aluminum alloy to a temperature between 150 and 170 degrees centigrade.

According to a further teaching of the present invention, the first heating is for a period of between 2 and 18 hours.

According to a further teaching of the present invention, there is also provided the step of waiting at least 24 hours after the immersing and thereafter performing the precipitation hardening.

According to a further teaching of the present invention, the cooling is to a temperature between 20 and 30 degrees centigrade.

According to a further teaching of the present invention, the second heating is to a temperature of between 155 and 165 degrees centigrade.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.

In the drawings:

FIG. 1 is a cross section of a lightweight opaque armor plate constructed and operational according to the teachings of the present invention;

FIG. 2 is a cross section of the armor plate of FIG. 1 deployed in the pocket of an attachment device constructed and operational according to the teachings of the present invention; and

FIG. 3 is a perspective view of an attachment system constructed and operational according to the teachings of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is armor plates having only two layers, a contiguous ceramic component and a hardened metal layer, and a method of producing the armor plate which can be employed to protect a target from damage caused by projectiles including, but not limited to, bullets.

Specifically, the present invention can be used to armor a vehicle or a portion thereof. Alternately, or additionally, the present invention may be employed to protect a structure such as a building or bus stop, or a portion thereof such as a window or a door. Alternately, the present invention may be employed as a portable bulletproof shelter for one or more people. Alternately, the present invention may be employed in construction of improved bulletproof clothing.

The principles and operation of lightweight armor plates and a method of production according to the present invention may be better understood with reference to the drawings and accompanying descriptions.

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

For purposes of this specification and the accompanying claims, the term “projectile” includes, but is not limited to, a bullet fired from a weapon such as, for example, an M-16, an AK-47 (i.e. Kalashnikov), a Galil assault rifle, an Uzi machine gun, a pistol, a rifle or similar. Projectile further includes a collection of small projectiles, for example buckshot fired from a shotgun shell or shrapnel from an explosive device. The following bullets are specifically included in the definition of projectile: AK-47 7.62×39AP; AK-47 7.62×51AP NATO; M16 5.56×45 33-109, M-80 Ball 7.62×51, Dragonov machinegun 7.62×54AP, and 7.62×61 AP Level Four NU Standard.

For purposes of this specification and the accompanying claims, the term “explosive device” includes, but is not limited to, a hand grenade, a pipe bomb and an explosive packet worn or carried by a suicide bomber. Specifically, suicide bombers are known to include small metal pieces (e.g. screws, nails) within the explosive packet to produce shrapnel. These small metal pieces are included within the definition of projectile.

For purposes of this specification and the accompanying claims, the term “impenetrable” indicates a capability of preventing penetration by a projectile fired from a weapon at a distance of fifty meters, more preferably four to five meters, most preferably zero to one meter from the armor plate.

Referring now to the drawings, FIGS. 1 and 2 depict a lightweight opaque armor plate 40 including a contiguous ceramic layer 44. Contiguous ceramic layer 44 absorbs and disperses energy from a projectile 20. Therefore, the ceramic layer 44 is generally considered to be the front of armor plate 40. The ceramic layer 44 receives the impact of the projectile, such as but not limited to, bullets and shrapnel. In the case of bullets, for example, the tip of the bullet is deformed and the pressure load is reduced by contact with the ceramic layer 44. Armor plate 40 further includes a hardened metal layer 46 situated behind, and fixedly attached to, the contiguous ceramic layer 44 and designed and constructed to prevent penetration by projectile. The high plastic elasticity of hardened metal layer 46 completely absorbs the rest of the kinetic energy of the bullet through deformation and heat. Attachment of ceramic layer 44 and hardened metal layer 46 is preferably by use of an adhesive 48.

Preferably, hardened metal layer 46 is constructed of heat-treated aluminum or a heat-treated alloy as described in more detail hereinbelow. For example, hardened metal layer 46 may be an alloy including at least one of the following materials, while not being limited to, aluminum, magnesium, silicon, zinc, titanium, copper, manganese and chromium.

Preferably opaque plate 40 is deployed in a removable attachment device 38, as illustrated in FIGS. 2 and 3, and/or is provided with a coating as described in more detail hereinbelow.

Preferably, contiguous ceramic layer 44 includes primarily Alumina (Al₂O₃), Magnesia (MgO) or a combination thereof. Preferably layer 44 is 96% Alumina, more preferably 98% Alumina, most preferably between 98% and 100% Alumina.

Preferably plate 40 is supplied in relatively small pieces so that a total weight of each piece does not exceed 20 kg, more preferably 15 kg, still more body shield, a portion of a helmet or a portable protective wall. Preferably, plate 40 is used in conjunction with an existing surface such as, for example, a car door. Most preferably plate 40 is removably attachable to an existing surface to render it bulletproof.

The heat-treated alloy may include, for example, magnesium, copper and silicon and/or combinations thereof. Thus, according different preferred embodiments of the invention, the hardened metal layer 46 may contain materials including, but not limited to, aluminum, magnesium, silicon, titanium, zinc, copper, manganese and chromium.

Examples of alloys known to be useful in construction hardened metal layer 46 are provided in Table 1. These compositions are provided as examples only and are not intended to limit the scope of the invention. One ordinarily skilled in the art of metallurgy will be able to adjust the exact composition of an alloy to slightly alter weight or elasticity by adding, for example, rare earth metals such as tungsten, molybdenum or beryllium according to guidelines set fort in metallurgy texts. Addition of small quantities of such metals to the alloy is within the scope of the present invention.

TABLE 1 Alloys useful in construction of hardened metal layers MATERIAL WEIGHT PERCENTAGE Magnesium (Mg) 0.3-5.0 Silicon (Si) 0.0-8.0 Titanium (Ti)  0.0-10.0 Copper (Cu) 0.0-5.0 Manganese (Mn) 0.0-1.0 Chromium (Cr) 0.0-5.0 Aluminum (Al) 70.0-90.0 Zinc (Zn)  0.0-10.0

Thus, according to some preferred embodiments of the invention hardened metal layer 46 may include 0.45 to 0.6% magnesium; 6.7 to 7.5% silicon; approximately 0.2% titanium and aluminum, for example 91.7 to 92.65% aluminum.

According to alternate preferred embodiments of the invention hardened metal layer 46 may include 2.1 to 2.9% magnesium; 1.2 to 2% copper; approximately 0.3% manganese; 0.18 to 0.35% chromium and aluminum, for example 94.45 to 96.22% aluminum.

According to additional alternate preferred embodiments of the invention hardened metal layer 46 may include 1.2% to 1.8% magnesium; 3.8 to 4.9% copper; approximately 0.3 to 0.9% manganese; and aluminum, for example 92.4 to 94.7% aluminum.

According to further additional alternate preferred embodiments of the invention hardened metal layer 46 may include 0.8 to 1.2% magnesium; 0.15 to 0.4% copper; approximately 0.4 to 0.8% silicon; and aluminum, for example 97.6 to 98.65% aluminum.

Methods for preparation of alloys are well known in the art and detailed description of common methods may be found, for example, in “Principles of Metal Casting” (Eds. Heine and Rosenthal, McGraw Hill Book Co.; 1955). and in “Symposium on Principles of Gating” published by the American Foundrymen's Society (1951) or in “Casting Aluminum” by C.W. Ammen (Tab Books Inc.; 1985) or in “Metallurgy of Aluminum Alloys by M. van Lancker (Chapman and Hall Ltd.; 1967). Each of these texts is fully included herein by reference.

The term “heat treatment” or “heat-treated” as used herein preferably refers to a process which includes precipitation hardening, tempering, solution treatment or combinations thereof. As used herein, the term “tempering” specifically includes rapid cooling, for example by immersion in a chilled water bath or ice and water slurry.

Thus, one method for preparation of a hardened metal alloy according to the teachings of the present invention includes solution treatment followed by tempering in an ice/water bath followed by precipitation hardening. This process imparts previously unachieved properties to the resultant alloy, for example elongation of 11-16%, as apposed to the 5-9% currently achieved in the art.

The solution treatment accomplishes the alloying of the metals in which the alloying metals either replace some of the base-metal atoms (substitutional solid solution) or occupy some of the space between the base-metal atoms (interstitial solid solution). In both cases, the base metal is distorted and the movement of dislocations is retarded, thereby hardening the metal. It should be noted that every fabric metal includes faults. These faults are generally referred to as “dislocations” The movement of the dislocations in the metal reduces the overall strength of the metal. The strength of the metal is increased by retarding the movement of the dislocations within the base-metal.

Solution treatment may be accomplished, for example by heating the alloy to a temperature in excess of 500 degrees centigrade, more preferably 540 to 550 degrees centigrade, most preferably approximately 543 degrees centigrade a period of two to eighteen hours. The alloy is subsequently cooled to less than 60 degrees centigrade, more preferably 20 to 30 degrees centigrade by immersion in a liquid bath, for example an ice water bath or chilled acetone/ethanol bath for four to ten seconds. This process imparts a “potential hardness” to the alloy.

Precipitation hardening may be accomplished by, for example, heating the alloy to a moderate temperature, preferably 150 to 170 degrees more preferably 155 to 165 degrees centigrade. Preferably, precipitation hardening is performed 24 hours or more after solution treatment.

This process increases the hardening of the metal by producing a “traffic” effect of the alloying elements that move rapidly and retard the dislocations, thereby strengthening the metal alloy.

These industrial processes are described in greater detail in American Standards MIL-A-21180 (casting); MIL-A-6088 (heat treatment) and MIL-ASTM-B26 (all published by the U.S. Government Printing office; 1971) which are fully incorporated herein by reference.

Preferably plate 40 is deployed in a removable attachment device 38 as mentioned hereinabove. Thus, attachment device 38 may be, for example, a sling 50 or a pocket 52, both of which include a pair of attachment hooks 54 and an attachment rod or band 56. Alternately, but also preferably, the attachment device may take the form of suction cups (not shown).

In order to facilitate ease of handling, plate 40 may further include a coating (not shown). The coating may be, for example, rubber, plastic or fabric. Preferably fabric coatings are bonded to plate 40 with a suitable adhesive.

An article of clothing modified to accommodate the at least one lightweight armor plate 40 may be produced, for example, by incorporating pockets designed to engage and retain one or more plates 40 into, for example, the legs of a pair of trousers. Alternately, or additionally, one or more plates 40 may be sown between layers of fabric when manufacturing a garment.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims. 

1. A lightweight armor plate, the plate comprising: (a) a single contiguous ceramic layer; and (b) a single hardened metal layer fixedly attached to said ceramic layer, and said single hardened metal layer is an alloy that contains at least one material selected from the group consisting of aluminum, magnesium, silicon, titanium, copper, manganese, zinc and chromium.
 2. The lightweight armor plate of claim 1, wherein said alloy is a heat-treated alloy.
 3. The lightweight armor plate of claim 1, wherein said hardened metal layer includes at least seventy percent aluminum by weight and further includes at least one element selected from the group consisting of magnesium, silicon, titanium, copper, manganese, chromium, zinc, beryllium, tungsten and molybdenum.
 4. The lightweight armor plate of claim 1, wherein said hardened metal layer is produced by heating said alloy to a temperature in excess of 540 degrees centigrade, followed by cooling said alloy to less than sixty degrees centigrade by immersion in a liquid bath and thereafter precipitation hardening said alloy by heating to a temperature between 100 and 170 degrees centigrade.
 5. The lightweight armor plate of claim 1, wherein said contiguous ceramic layer includes primarily at least one material selected from the group consisting of Alumina (Al2O3) and Magnesia (MgO).
 6. A method for producing a hardened metal plate for use in an armor plate, the method comprising the steps of: (a) heating an aluminum alloy to a temperature in excess of 540 degrees centigrade; (b) immersing said aluminum alloy in a liquid bath, thereby cooling to less than 60 degrees centigrade; and (c) precipitation hardening by second heating said aluminum alloy to a temperature between 150 and 170 degrees centigrade.
 7. The method of claim 6, wherein said first heating is for a period of between 2 and 18 hours.
 8. The method of claim 6, further including the step of waiting at least 24 hours after said immersing and thereafter performing said precipitation hardening.
 9. The method of claim 6, wherein said cooling is to a temperature between 20 and 30 degrees centigrade.
 10. The method of claim 6, wherein said second heating is to a temperature of between 155 and 165 degrees centigrade. 